The applications of touch input devices are very extensive. In the early stage, a touch input device is installed on a notebook computer. By operating the touch input device, the movement of a cursor may be controlled or a corresponding icon of a user interface may be clicked without the need of using a mouse to operate the notebook computer. With the advance of science and technology, a physical button may be integrated into the touch input device, so that the touch input device has a button function. Under this circumstance, it is not necessary to install plural physical buttons on the peripheral area of the touch input device. Since the physical button is integrated into the touch input device, the layout space is saved and the outward appearance is aesthetically-pleasing.
Hereinafter, a conventional touch input device with a button function will be illustrated. For example, this touch input device is disclosed in US Patent Publication No. 2011/0310029. The touch input device comprises a housing body, a touch sensitive layer, a triggering switch, plural foot pads, a foot bar, and a hinge structure. The triggering switch, the foot bar and the hinge structure are disposed on a frame of the touch input device. When a downward force is received by the conventional touch input device, the touch sensitive layer detects the downward force and correspondingly generates a first signal. Then, the foot bar is pushed by the plural foot pads. In response to the downward force, the foot bar is swung relative to a hinge line of the hinge structure. Consequently, the triggering switch is triggered to generate a second signal. According to the first signal or the second signal, the touch input device outputs a corresponding control signal. According to the control signal, a corresponding command is executed.
For assembling the conventional touch input device having the button function, the triggering switch is firstly disposed on the frame, and the frame is disposed under the touch sensitive layer. When the downward force is received by the conventional touch input device, the triggering switch is moved to a position near the touch sensitive layer. Consequently, a sound box effect occurs within the housing body. Due to the sound box effect, a large collision sound is generated. Moreover, when the downward force is received by the conventional touch input device, the lever arm of swinging the foot bar is equal to the distance between the hinge line of the hinge structure and the plural foot pads. In addition, the distance between the hinge line of the hinge structure and the plural foot pads is very short. As known, the magnitude of a torque is equal to the product of the magnitude of a force multiply the length of a lever arm. Since the distance between the hinge line of the hinge structure and the plural foot pads is very short, the magnitude of the applied force should be large enough to swing the foot bar. From the above discussions, the conventional touch input device wastes energy. Moreover, since the magnitude of the applied force is very large, the collision sound is very large.
Therefore, there is a need of providing a touch input device with a button function in order to reduce the collision sound and save the energy.